Fex-M3d
a later variation on the original Fex-M3 nerve gas, Fex-M3d was designed to bind to neuro-receptors as it passed through the bloodstream after being inhaled. This binding effect prevents the nerves from sending information to the brain. In small doses, it can cause involuntary muscles to become lax, making the heartbeat irregular and breathing difficult. In larger doses, the body's autonomous nervous system shuts down completely, stopping the lungs from breathing.